Nature “Siberian Tiger Quest” at 7 pm
Chris Morgan has tracked large predators in some of the wildest and most remote places on Earth. He now embarks on his greatest challenge – to find and film the Siberian tiger living wild and free in Russia’s far eastern forests. This film features the work of Korean cameraman, Sooyong Park, who spent two years in the forest tracking and filming the world’s biggest cat. Park’s tracking technique was very unconventional. He dug himself into an underground pit and, incredibly, waited there for weeks at a time, hoping for a glimpse of a wild tiger. Morgan adopts the same method while he shares with us firsthand the difficulty of seeing the rare Siberian tiger.

NOVA “Secrets of the Viking Sword” at 8 pm
The Vikings were among the fiercest warriors of all time. Yet only a select few carried the ultimate weapon of their era: the feared Ulfberht sword. Fashioned using a process that would remain unknown to the Vikings’ rivals for centuries, the Ulfberht was a revolutionary high-tech tool as well as a work of art. Considered one of the greatest swords ever made, it remains a fearsome weapon more than a millennium after it last saw battle. But how did Viking sword makers design and build the Ulfberht, and what was its role in history? Now, NOVA uses cutting edge science and old-fashioned detective work to reconstruct the Ulfberht and finally unravel the “Mystery of the Viking Sword.”

NOVA ScienceNow “What Makes Us Human?” at 9 pm
Scientists have struggled for centuries to pinpoint the qualities that separate human beings from the millions of other animals who have evolved on this planet. David Pogue explores the traits we once thought were uniquely ours – language, tool-making, even laughter – to uncover their evolutionary roots. He traces some of the crucial steps that transformed cave men to accountants – and learns how much of his own DNA came from a Neanderthal ancestor.